The present invention relates to a sewing machine and more particularly relates to an overolock sewing machine having a cutter mechanism for cutting the edge of work while the work is to sewn, wherein a blade which is activated may be kept stopped and held as placed under the needle plate in case a stitching operation is performed without use of the cutter mechanism.
It is generally known that the overlock sewing machine is provided with a work edge cutting mechanism including a movable blade which may be operatively disconnected from a drive source in case the stitching operation is performed without use of the work edge cutting mechanism. This type of sewing machine is disclosed in the Japanese patent application laid open Hei.11-235489. The sewing machine is described as follows; An upper blade 16 is operated in association with a link 28 which is vertically reciprocated by rotation of an eccentric cam 27, because the vertical reciprocation of the link 28 is transmitted to the upper blade 16 through a first arm 29, a second arm 30, a blade holder 22 and a holder guide 23. The upper blade 16 may be disconnected from the vertically reciprocating link 28 by manipulation of a changeover lever 38 in case the stitching operation is performed without use of the work edge cutting mechanism, the changeover lever 38 being operated to pull out a connecting pin 34 from an operative position to disconnect the first arm 29 and the second arm 30 from each other.
According to the sewing machine, the work edge cutting mechanism is so formed as to keep the upper blade as is stopped in a region where the upper blade is operated in case the upper blade is disconnected from a drive source. In the operative region, the upper blade is vertically moved to cut the work edge between an upper position and a lower position where the upper blade is partly located above the needle plate where the work is handled by the user to be sewn. The upper blade is, therefore, something in the way in the stitching operation in case the stitching operation is performed without use of the upper blade. It is, therefore, an object of the invention to eliminate the defects and disadvantages of prior art. More precisely, it is an object of the invention to disconnect the upper blade from the drive source and move the same into a retreat position where the upper blade is not in the way of stitching operation in case the stitching operation is performed without use of the upper blade, and to connect the upper blade to the drive source and revert the same into the operative region in case the stitching operation is performed with use of the upper blade.